Radar systems typically utilize a large scanning antenna array mounted on a rotating platform to revolve the antenna array in the azimuth direction. These rotatable platforms allow the array to be oriented at a particular azimuth angle, or to sweep the array through an entire range of azimuth angles at a predetermined angular rate. In traditional rotating radar systems, one end of the antenna array is pivotally mounted to the rotating platform, forming a cantilevered arrangement in which the array can be tilted to a desired elevation angle with respect to the ground by, for example, a hydraulic linear actuator. In this cantilevered configuration the antenna array often has a center of mass offset vertically and/or horizontally from the center of the rotating platform. The hydraulic actuator and tilting arrangement used to set the tilt angle can create in inaccuracies in the positioning of the antenna array. This is known as the system's pointing error.
Traditional approaches used to rotate the platforms include various conventional drive systems supported by numerous rolling element bearings. These bearings, most notably the main support bearings of the rotatable platforms, are subject to significant load from both the weight of the cantilevered antenna arrays, as well as the large forces acting thereon from dynamic imbalances and wind/ice/snow acting on the exposed surfaces of the antenna array due to above-described offset of the center of mass. These forces can result in the fatigue and eventual failure of the bearings and other driveline components.
Further, the rotational motion of the antenna arrays necessitates the use of components such as slip-rings, for providing the array with power, as well as rotary joints for providing liquid coolant. In addition to reliability issues, slip-rings impose significant power limitations on the system. Likewise, rotary fluid joints are prone to leaking.
Accordingly, a system which eliminates the inherent drawbacks of rotating antenna arrangements is desired, as well as a system that eliminates the need for the typical separate subsystems for leveling the radar base, tilting the antenna array, and rotating it.